Preparation process and product of composite magnetic body

Abstract

The present application relates to the field of magnetic material processing, and discloses a preparation process and product of a composite magnetic body. A preparation process of a composite magnetic body comprises the following steps: S1, pressing a first powder to obtain a core body; S2, coating a second powder on the core body and pressing it to form a coating layer on the outer surface of the core body to obtain a composite body; S3, vacuum sintering the composite body to obtain a molded composite body; S4, cutting, electroplating, and magnetizing the molded composite body to obtain a composite magnetic body; the first powder is neodymium iron boron magnetic powder, and the second powder is iron powder; the iron powder is pretreated iron powder, and the pretreated iron powder is made of 96-98wt% iron powder and 2-4wt% adhesive. The composite magnetic body prepared in this application has low cost, the coating layer has good density, and the prepared composite magnetic body has stable magnetic properties and good mechanical strength.

Description

Technical Field

[0001] The present application relates to the field of magnetic material processing, and more specifically, to a preparation process and product of a composite magnetic body. Background Art

[0002] Neodymium iron boron magnets are based on the intermetallic compound Nd2Fe 14 B is the basis of permanent magnetic material. NdFeB magnets are divided into sintered NdFeB and bonded NdFeB. Bonded NdFeB is magnetic in all directions and corrosion-resistant. Sintered NdFeB is easy to corrode, so the surface needs to be plated, generally with zinc, nickel, environmentally friendly zinc, environmentally friendly nickel, environmentally friendly nickel-copper-nickel, etc.

[0003] Taking sintered NdFeB magnets as an example, the components of sintered NdFeB magnets are rare metals, which makes the cost of NdFeB magnets high and is not conducive to industrial large-scale production.

[0004] To reduce the cost of NdFeB magnets, existing techniques typically add metal powders that are magnetic or capable of interacting with magnetic materials. While this metal powder reduces the cost of NdFeB magnets, the bonding between the metal powder and the NdFeB magnet is poor, reducing the magnetic properties and mechanical strength of the resulting NdFeB magnets. Summary of the Invention

[0005] In order to solve the problem that the bonding performance between metal powder and NdFeB magnet in existing low-cost sintered NdFeB magnets is poor, thereby reducing the magnetic properties and mechanical strength of the obtained NdFeB magnets, the present application provides a preparation process and product of a composite magnetic body.

[0006] In a first aspect, the present application provides a process for preparing a composite magnetic body, which adopts the following technical solution:

[0007] A process for preparing a composite magnetic body comprises the following steps:

[0008] S1, pressing the first powder into a mold to obtain a core;

[0009] S2, coating the core with the second powder and performing pressing to form a coating layer on the outer surface of the core to obtain a composite body;

[0010] S3, vacuum sintering the composite body to obtain a formed composite body;

[0011] S4, cutting, electroplating, and magnetizing the formed composite body to obtain a composite magnetic body;

[0012] The first powder material is NdFeB magnetic powder, and the second powder material is iron powder; the iron powder is pretreated iron powder, which is made from 96-98wt% iron powder and 2-4wt% binder. By adopting the above technical solution, NdFeB magnetic powder is used as the first powder material and pressed into the desired shape and size, so that the magnetic powder reaches a certain density, and a core body is produced. This allows the core body to achieve a dense structure with high magnetic properties during sintering, while maintaining the orientation degree obtained during the magnetic field orientation process, thereby improving the magnetic properties and mechanical strength of the resulting composite magnetic body. Iron powder is then used as the second powder material and coated on the outer surface of the core body. After pressing, a dense and strong coating is formed on the surface of the core body to produce a molded composite body. The coating formed by the iron powder reduces the amount of NdFeB magnetic powder used and reduces the cost of the resulting composite magnetic body. By pretreating the iron powder with a relatively high weight of adhesive to obtain pretreated iron powder, the bonding strength between the coating layer and the core can be significantly improved, further improving the magnetic stability and mechanical strength of the composite magnetic body obtained. If the amount of adhesive added is too large, it is easy for the coating layer to have pores during the sintering process, which will reduce the density of the composite magnetic body obtained. The obtained molded composite body is then vacuum sintered. During the sintering process, the grain size of the NdFeB magnetic powder and the iron powder is reduced, the grain boundary area is increased, the density is enhanced, and at the same time, the bonding density between the NdFeB magnetic powder and the iron powder is enhanced, thereby improving the magnetic properties and mechanical strength of the composite magnetic body obtained. The composite magnetic body is then cut, and a protective layer is formed on the outer surface by electroplating. Finally, magnetization is performed to obtain the composite magnetic body with stable magnetic properties and mechanical strength of the present application.

[0013] Preferably, the core body is subjected to vacuum sintering before being coated with the second powder.

[0014] By adopting this technical solution, the core is vacuum sintered before being coated with the second powder. This effectively reduces the core's internal porosity, making the core structure more compact and improving the magnetic properties and mechanical strength of the resulting composite magnetic body. Furthermore, the pre-sintered core surface is smoother, further enhancing the composite magnetic body's magnetic stability.

[0015] Preferably, the neodymium iron boron magnetic powder is composed of a first magnetic powder and a second magnetic powder in a weight ratio of (2-3):1, the particle size of the first magnetic powder is 15-20 μm, and the particle size of the second magnetic powder is 6-10 μm; the iron powder is composed of a first iron powder and a second iron powder in a weight ratio of (1-2):1, the particle size of the first iron powder is 10-12 μm, and the particle size of the second iron powder is 0.05-3 μm.

[0016] By adopting the above technical solution, the particle size of the NdFeB magnetic powder and the particle size of the iron powder are optimized, further improving the overall magnetic properties and mechanical strength of the resulting composite magnetic body. The large-particle size of the first magnetic powder and the small-particle size of the second magnetic powder work together to increase the contact area between the NdFeB magnetic powder grains, fill the gaps, improve density and uniformity, and thus enhance magnetic properties and mechanical strength. The large-particle size of the first iron powder and the small-particle size of the second iron powder work together, with the particle size of the first iron powder between the first and second magnetic powders and the particle size of the second iron powder being smaller. This allows the iron powder to stably bond with the core during sintering to form a denser structure, further improving the magnetic properties and mechanical strength of the composite magnetic body.

[0017] Preferably, the sintering temperature in step S3 is 1000-1200° C., and the sintering time is 2-4 hours.

[0018] By adopting the above technical solution and controlling the optimal sintering temperature and sintering time, the density and compactness of the composite magnetic body can be effectively improved, thereby enhancing its magnetic properties and mechanical strength. At the same time, internal defects in the composite magnetic body can be reduced, and the consistency and stability of the composite magnetic body can be improved.

[0019] Preferably, the thickness ratio of the core and the cladding layer is (4-6):1.

[0020] By adopting the above technical solution and controlling the thickness ratio of the core and coating layer to achieve the optimal thickness, the overall performance of the composite magnetic body can be effectively improved, cracking and deformation of the composite magnetic body can be prevented, and the reliability and stability of the composite magnetic body can be enhanced. If the coating layer is too thick, the magnetic properties of the composite magnetic body can be easily affected. If the coating layer is too thin, the mechanical strength of the composite magnetic body can be easily affected.

[0021] Preferably, the adhesive is made from the following raw materials in percentage by weight:

[0022] Tackifier 5-8%

[0023] Dispersant 2-5%

[0024] Structural regulator 6-10%

[0025] Solvent residue.

[0026] By adopting the above technical solution, the adhesive is composed of a thickener, a dispersant, a structure regulator and a solvent in an optimal weight ratio, and the components cooperate with each other to effectively improve the bonding stability between the iron powder particles, so that the iron powder can form a stable and dense coating layer during vacuum sintering while stably combining with the core to form a dense and stable composite magnetic body. Under the synergistic dispersing effect of the solvent and the dispersant, the iron powder can be evenly dispersed, reducing the occurrence of caking or agglomeration, and improving the uniformity and consistency of the coating layer. The thickener is dispersed into the iron powder, enhancing the adhesion between the iron powder particles and between the iron powder and the NdFeB magnetic powder, further improving the coating density and structural stability of the coating layer. During the vacuum sintering process, under the synergistic bonding effect of the thickener, the structure regulator can play a better bonding role on the iron powder and the NdFeB magnetic powder during high-temperature sintering, further improving the density of the sintered coating layer, and at the same time improving the bonding stability of the coating layer and the core.

[0027] Preferably, the viscosity enhancer is composed of propylene glycol alginate, hydroxypropyl distarch phosphate and 3-diethylenetriaminopropyltrimethoxysilane in a weight ratio of 1:(0.2-0.4):(0.1-0.2).

[0028] By adopting the above technical solution, propylene glycol alginate, hydroxypropyl distarch phosphate and 3-diethylenetriaminopropyltrimethoxysilane in a relatively optimal weight ratio are used as thickeners to have a good synergistic effect, forming a uniform thickening system, which can significantly improve the binding force between iron powder particles and the bonding stability between iron powder and core, thereby improving the overall structural stability and mechanical strength of the composite magnetic body.

[0029] Preferably, the dispersant is sodium polyacrylate, and the solvent is water, propylene glycol and / or ethylene glycol.

[0030] By adopting the above technical solution, sodium polyacrylate as a dispersant can effectively improve the uniform dispersion of iron powder. Using water, propylene glycol, and / or ethylene glycol as solvents can improve the overall fluidity of the adhesive, further promoting the uniform mixing of the components and enhancing the adhesive's bonding stability. During vacuum sintering, the adhesive can be evenly decomposed without affecting the density of the coating layer.

[0031] Preferably, the structure regulator is composed of zinc oxide and tin oxide in a weight ratio of (1-1.5):1.

[0032] By adopting the above technical solution, using zinc oxide and tin oxide in a relatively optimal weight ratio as structural regulators, it is possible to promote grain refinement during high-temperature sintering, form an alloy structure with iron, effectively improve the internal structure of the composite magnetic body, reduce defects and porosity during the sintering process, and improve the mechanical strength and magnetic properties of the resulting composite magnetic body.

[0033] In a second aspect, the present application provides a composite magnetic body, which adopts the following technical solution:

[0034] A composite magnetic body is prepared by the above preparation process.

[0035] By adopting the above technical solution, the composite magnetic body prepared in the present application has good magnetic performance stability and mechanical strength while having low cost.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. The preparation process of the composite magnetic body of the present application improves the bonding performance between the metal powder and the NdFeB magnetic powder by coating the pretreated iron powder made of adhesive and iron powder on the outer surface of the core formed by NdFeB magnetic powder, thereby solving the problem of poor bonding between the metal powder and NdFeB magnetic powder. The prepared composite magnetic body has stable magnetic properties and good mechanical strength while being low in cost.

[0038] 2. By optimizing the particle size of iron powder and NdFeB magnetic powder, the contact area between the grains of NdFeB magnetic powder is increased, the gaps are filled, and the density and uniformity are improved; at the same time, during the sintering process, the iron powder and the core can be stably combined to form a denser structure, further improving the magnetic properties and mechanical strength of the composite magnetic body.

[0039] 3. Using propylene glycol alginate, hydroxypropyl distarch phosphate and 3-diethylenetriaminopropyltrimethoxysilane in an optimal weight ratio as thickeners, and using zinc oxide and tin oxide in an optimal weight ratio as structure regulators, the thickeners are dispersed in the iron powder, thereby enhancing the adhesion between the iron powder particles and between the iron powder and the NdFeB magnetic powder, further improving the coating density and structural stability of the coating layer. During the vacuum sintering process, under the synergistic bonding effect of the thickener, the structure regulator can promote grain refinement during high-temperature sintering, form an alloy structure with iron, effectively improve the internal structure of the composite magnetic body, reduce defects and porosity during the sintering process, and improve the mechanical strength and magnetic properties of the composite magnetic body. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to the embodiments.

[0041] The following are the sources and specifications of some raw materials of this application. The raw materials used in the preparation examples and examples of this application can be obtained from commercial sources, including but not limited to the following models and manufacturers. Raw materials with equivalent performance can be used:

[0042] 1. NdFeB magnetic powder: N50 NdFeB magnetic powder;

[0043] 2. Iron powder: Yinbai brand, atomized spherical iron powder;

[0044] 3. Sodium polyacrylate: Dow 445N or Dow dispersant OROTAN 731A;

[0045] 4. Zinc oxide: particle size 30-50nm, content 99.7%;

[0046] 5. Tin oxide: particle size 30-50nm, content 99.9%.

[0047] Preparation example of adhesive

[0048] Preparation Example 1

[0049] Preparation Example 1 discloses an adhesive prepared by the following steps:

[0050] 0.8 kg of sodium carboxymethyl cellulose as a thickener and 0.2 kg of a dispersant (composed of polyethylene glycol 400 and 445N in a weight ratio of 2:1) were added to 8.4 kg of a solvent (composed of water and propylene glycol in a weight ratio of 2:1), and after stirring and dispersing, 0.6 kg of tin oxide as a structure regulator was added and dispersed evenly to prepare an adhesive.

[0051] Preparation Example 2-3

[0052] The difference between Preparation Example 2-3 and Preparation Example 1 is that the amount of raw materials used and the preparation conditions are different. Please refer to Table 1 below for details.

[0053] Table 1 Parameters of Preparation Examples 1-3

[0054]

[0055] Preparation Example 4

[0056] The difference between Preparation Example 4 and Preparation Example 1 is that the thickener is different. The thickener in Preparation Example 4 is composed of sodium carboxymethyl cellulose, hydroxypropyl distarch phosphate and vinyl trimethoxysilane in a weight ratio of 1:0.2:0.1, and the rest is the same as Preparation Example 1.

[0057] Preparation Example 5

[0058] The difference between Preparation Example 5 and Preparation Example 4 is that the viscosity enhancer in Preparation Example 5 is composed of propylene glycol alginate, hydroxypropyl distarch phosphate and 3-diethylenetriaminopropyltrimethoxysilane in a weight ratio of 1:0.2:0.1, and the rest is the same as Preparation Example 4.

[0059] Preparation Example 6

[0060] The difference between Preparation Example 6 and Preparation Example 4 is that the viscosity enhancer in Preparation Example 6 is composed of propylene glycol alginate, hydroxypropyl distarch phosphate and 3-diethylenetriaminopropyltrimethoxysilane in a weight ratio of 1:0.4:0.2, and the rest is the same as Preparation Example 4.

[0061] Preparation Example 7

[0062] The difference between Preparation Example 7 and Preparation Example 5 is that the dispersant in Preparation Example 7 is polyacrylate sodium salt, specifically sodium polyacrylate 445N, and the rest is the same as Preparation Example 5.

[0063] Preparation Example 8

[0064] The difference between Preparation Example 8 and Preparation Example 5 is that the dispersant in Preparation Example 8 is polyacrylic acid sodium salt, specifically Dow dispersant OROTAN 731A, and the rest is the same as Preparation Example 5.

[0065] Preparation Example 9

[0066] The difference between Preparation Example 9 and Preparation Example 7 is that the structure adjusting agent in Preparation Example 9 is composed of zinc oxide and tin oxide in a weight ratio of 1:1, and the rest is the same as Preparation Example 7.

[0067] Preparation Example 10

[0068] The difference between Preparation Example 10 and Preparation Example 7 is that the structure adjusting agent in Preparation Example 10 is composed of zinc oxide and tin oxide in a weight ratio of 1.5:1, and the other components are the same as Preparation Example 7.

[0069] Example

[0070] Example 1

[0071] Example 1 discloses a process for preparing a composite magnetic body, comprising the following steps:

[0072] S1. Using a magnetic field forming press, NdFeB magnetic powder is pressed as a first powder material, wherein the NdFeB magnetic powder is composed of a first magnetic powder and a second magnetic powder in a weight ratio of 2:1, wherein the particle size of the first magnetic powder is 15-20 μm and the particle size of the second magnetic powder is 6-10 μm, and a core is obtained after pressing;

[0073] S2. Pretreated iron powder is used as a second powder, coated on the core and continued to be pressed using a magnetic field forming press, wherein the pretreated iron powder is composed of 96 wt% iron powder and 4 wt% of the binder prepared in Preparation Example 1, and the iron powder is composed of a first iron powder and a second iron powder in a weight ratio of 1:1, the particle size of the first iron powder is 10-12 μm, and the particle size of the second iron powder is 0.05-3 μm. A coating layer is formed on the outer surface of the core, and the thickness ratio of the core to the coating layer is controlled to be 6:1 to obtain a composite;

[0074] S3, the composite body is sintered in a furnace with the temperature of 1000℃ and sintered for 4h under a vacuum of 1×10 - 3 The composite body was obtained by vacuum sintering under the condition of Pa.

[0075] S4. Cut the formed composite body and electroplate it on an automatic nickel plating line using a nickel plating liquid to form a 10μm nickel plating layer. Then, use a multi-pole magnetizer to magnetize it with a magnetizing voltage of 3000V, a capacitance of 5000μF, and a magnetizing time of 1s to obtain a composite magnetic body. The nickel plating liquid is a commercially available nickel plating liquid for magnets, and the model here is not limited.

[0076] Example 2-3

[0077] The difference between Example 2-3 and Example 1 is that the process parameters are different, see Table 2 below for details.

[0078] Table 2 Parameters of Examples 1-3

[0079]

[0080]

[0081] Example 4

[0082] The difference between Example 4 and Example 1 is that in step S1, the core obtained after pressing is heated at a temperature of 1000°C and a vacuum degree of 1×10 -3 Pa under vacuum sintering conditions for 1 h, and then proceed to step S2. Other steps are the same as in Example 1.

[0083] Example 5

[0084] The difference between Example 5 and Example 1 is that the second magnetic powder is replaced by the first magnetic powder in equal amount, and the rest is the same as Example 1.

[0085] Example 6

[0086] The difference between Example 6 and Example 1 is that the first iron powder is replaced by the second iron powder in equal amount, and the rest is the same as Example 1.

[0087] Examples 7-13

[0088] The difference between Examples 7-13 and Example 1 is that the sources of the binder in the pretreated iron powder are different, see Table 3 below for details.

[0089] Table 3 Sources of adhesives for Examples 7-13

[0090]

[0091]

[0092] Comparative Example

[0093] Comparative Example 1

[0094] The difference between Comparative Example 1 and Example 1 is that in step S2, iron powder is directly used as the second powder, and the iron powder is composed of a first iron powder and a second iron powder in a weight ratio of 1:1. The particle size of the first iron powder is 10-12 μm, and the particle size of the second iron powder is 0.05-3 μm. The rest is the same as Example 1.

[0095] Comparative Example 2

[0096] The difference between Comparative Example 2 and Example 1 is that the amount of pretreated iron powder used is 90 wt %, the amount of adhesive used is 10 wt %, and the rest is the same as Example 1.

[0097] Performance testing

[0098] The following performance tests were conducted on the composite magnetic bodies prepared in Examples 1-13 and Comparative Examples 1-2, using composite magnetic bodies with a D20*5 mm size as test samples:

[0099] 1. Remanent magnetism detection:

[0100] Use a permanent magnet property tester to test the remanence Br (unit: kGs) of the composite magnetic body, and record the test results; 2. Compressive strength test:

[0101] Use a pressure testing machine to apply test pressure to the composite magnetic body, record the pressure value when the composite magnetic body breaks, and record it as the compressive strength (unit: kN / mm 2 ), test and record the test results;

[0102] The following are performance test data of the composite magnetic bodies of Examples 1-13 and Comparative Examples 1-2. For details, see Table 4 below.

[0103] Table 4 Performance data of composite magnetic bodies of Examples 1-13 and Comparative Examples 1-2

[0104]

[0105]

[0106] Combining Examples 1-3 and Comparative Example 1 with Table 4, it can be concluded that the composite magnetic body obtained by using the pretreated iron powder of the present application as a coating layer and vacuum sintering it with a core body has higher remanence and better compressive strength.

[0107] Combining Examples 1-3 and Examples 7-13 with Table 4, it can be concluded that further optimizing the component ratio of the binder used in the pre-treated iron powder can further improve the magnetic properties and mechanical strength of the resulting composite magnetic body. Compared to Examples 1 and 7, Examples 8-9 further optimize the ratio and amount of the thickener in the binder, and the remanence of the resulting composite magnetic body is increased by 0.31 kGs, and the compressive strength is also significantly increased by 0.28 kN / mm. 2 , which may be because the thickener improves the density and adhesion of the iron powder, thereby improving the overall mechanical strength of the composite magnetic body obtained. Compared with Example 8, Examples 10-11 further optimize the type of dispersant, and the residual magnetic properties and compressive strength of the composite magnetic body obtained are also improved. Compared with Example 10, Examples 12-13 further optimize the components and ratios of the structural adjustment agent, and the residual magnetism of the composite magnetic body obtained is significantly improved to 13.96 / kGs, and the compressive strength is also increased to 1.42kN / mm 2 This is likely because the superior structure modifier improves the structural density of the coating layer under high-temperature sintering conditions, thereby enhancing the magnetic properties and mechanical strength of the resulting composite magnetic body. In contrast, in Comparative Example 2, the amount of binder was increased compared to Example 1, resulting in decreased magnetic properties and mechanical strength of the resulting composite magnetic body. This is likely because the excessive amount of viscosity enhancer creates pores and voids during vacuum sintering, which in turn reduces the performance of the resulting composite magnetic body.

[0108] Combining Examples 1-3 and Example 4 and Table 4, it can be concluded that in Example 4, the core was sintered before coating the second powder, and the remanence and compressive strength of the composite magnetic body obtained were slightly reduced, but the change was not significant; while in Example 5, large-particle first magnetic powder was used for all NdFeB magnetic powders, and the remanence and compressive strength of the composite magnetic body obtained were reduced. This may be because the sintering consistency of the large-particle first magnetic powder alone was low, which reduced the bonding performance of the core and the coating layer, resulting in reduced performance of the composite magnetic body. In Example 6, small-particle second iron powder was used for all iron powders, and the remanence and compressive strength of the composite magnetic body obtained were reduced. This may be because the small-particle second iron powder alone reduced the contact area between the iron powder particles, reducing the density of the coating layer after sintering, thereby reducing the magnetic properties and mechanical strength of the composite magnetic body obtained.

[0109] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A process for preparing a composite magnetic body, characterized in that: The following steps are involved: S1, pressing the first powder into a mold to obtain a core; S2, coating the core with the second powder and performing pressing to form a coating layer on the outer surface of the core to obtain a composite body; S3, vacuum sintering the composite body to obtain a formed composite body; S4, cutting, electroplating, and magnetizing the formed composite body to obtain a composite magnetic body; The first powder material is neodymium iron boron magnetic powder, and the second powder material is iron powder; the iron powder is pretreated iron powder, and the pretreated iron powder is prepared from 96-98wt% iron powder and 2-4wt% binder.

2. The process for preparing a composite magnetic body according to claim 1, wherein: The core body is first subjected to vacuum sintering before being coated with the second powder.

3. A process for preparing a composite magnetic body according to claim 1 or 2, characterized in that: The NdFeB magnetic powder is composed of a first magnetic powder and a second magnetic powder in a weight ratio of (2-3):1, the particle size of the first magnetic powder is 15-20µm, and the particle size of the second magnetic powder is 6-10µm; the iron powder is composed of a first iron powder and a second iron powder in a weight ratio of (1-2:1), the particle size of the first iron powder is 10-12µm, and the particle size of the second iron powder is 0.05-3µm.

4. The process for preparing a composite magnetic body according to claim 1, wherein: The sintering temperature in step S3 is 1000-1200° C., and the sintering time is 2-4 hours.

5. The process for preparing a composite magnetic body according to claim 1, wherein: The thickness ratio of the core and the cladding layer is (4-6):

1.

6. The process for preparing a composite magnetic body according to claim 1, characterized in that: The adhesive is prepared from the following raw materials in percentage by weight: Tackifier 5-8% Dispersant 2-5% Structural adjustment agent 6-10% Solvent residue.

7. The process for preparing a composite magnetic body according to claim 6, characterized in that: The viscosity enhancer consists of propylene glycol alginate, hydroxypropyl distarch phosphate and 3-diethylenetriaminopropyltrimethoxysilane in a weight ratio of 1:(0.2-0.4):(0.1-0.2).

8. The process for preparing a composite magnetic body according to claim 6, characterized in that: The dispersant is polyacrylic acid sodium salt, and the solvent is water, propylene glycol and / or ethylene glycol.

9. The process for preparing a composite magnetic body according to claim 6, characterized in that: The structure regulator is composed of zinc oxide and tin oxide in a weight ratio of (1-1.5):

1.

10. A composite magnetic body, characterized in that: The invention is prepared by the preparation process according to any one of claims 1 to 9.

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